The aim of this project is to investigate the biosynthesis of cephalotaxine and the esterified Cephalotaxus alkaloids harringtonine, deoxyharringtonine, and isoharringtonine. BIBLIOGRAPHIC REFERENCES: R.J. Parry, "Biosynthesis of the Securinega Alkaloids. Stereospecificity of Hydrogen Loss from C-3 of Tyrosine", Chem. Commun., 144 (1975). R.J. Parry and J.M. Schwab, "Biosynthesis of Cephalotaxus Alkaloids. I. Novel Mode of Tyrosine Incorporation into Cephalotaxine," J. Amer. Chem. Soc., 97, 2555 (1975).